Information storage devices are used to retrieve and/or store data in computers and other consumer electronics devices. A magnetic hard disk drive is an example of an information storage device that includes one or more magnetic heads that can both read and write, but other information storage devices also include heads—sometimes including heads that cannot write.
In a magnetic hard disk drive, the head typically comprises a body called a “slider” that carries a magnetic transducer on its trailing end. The magnetic transducer typically comprises a writer and a read element. The magnetic transducer's writer may be of a longitudinal or perpendicular design, and the read element of the magnetic transducer may be inductive or magnetoresistive. In a magnetic hard disk drive, the transducer is typically supported in very close proximity to a spinning magnetic disk by a hydrodynamic air bearing. As a motor rotates the magnetic disk, the hydrodynamic air bearing is formed between an air bearing surface of the slider of the head and a surface of the magnetic disk. The thickness of the air bearing at the location of the transducer is commonly referred to as the “mechanical flying height.”
The magnetic disk typically includes several layers near its surface. Information is stored magnetically in a hard magnetic layer. A protective layer including carbon typically covers the hard magnetic layer for wear and corrosion resistance. The hard magnetic layer is typically supported by one or more underlayers with desired surface and/or properties. For example, in perpendicular recording applications, a magnetically soft underlayer may help channel magnetic flux beneath the hard magnetic layer. The magnetic transducer of the head and the hard magnetic layer of the disk are typically separated by both the air bearing and the disk protective layer(s). This separation is typically referred to as the “magnetic head-disk spacing,” the “magnetic spacing,” or the “magnetic flying height.”
Modern magnetic transducers may include a magnetic shield to shunt write fields in the off track direction, thus facilitating high track density magnetic recording. However, the presence of the side shields may worsen wide area track erasure (“WATER”) due to excessive off track write field and interactions with the domain walls of the side shield. To reduce WATER and reduce off track writing, a side shield having a longer throat height is preferred. However, to reduce write field rise time and increase data rate for writing on track, a side shield having a shorter throat height is preferred.
Accordingly, what is needed in the art is a shielded write transducer design that improves the engineering trade-off between off-track and on-track writing performance.